Remote control apparatus



2 Sheets-Sheet A. v. EASTMAN ammo'm CONTROL APPARATUS Original FiledJan. 26, 1925 1.. I'YY' no VOLTS E .uxovous llrl II ll [/0 VOLTS //0VOLTS His Annorne 1, 1931. A. V. EASTMAN REMOTE CONTROL APPARATUSOriginal Filed Jan. 26, 1925 2 Sheets-Sheet 2 Fig.4.

Inve nno r I\% .uulv 2m s b a b v. m n v. H u S u A Patented Dec. 1,1931 UNITED STATES PATENT OFFICE.

AUSTIN V. EASTMAN, OF SEATTLE, WASHINGTON, ASSIGNOR TO GENERAL ELECTRICCOMPANY, CORPORATION OF NEW YORK REMOTE CONTROL APPARATUS Applicationfiled January 26, 1925, Serial No. 4,781. Renewed December 5, 1930.

The present invention relates to means for transmitting and receivinghigh frequency currents over a power distribution system.

One of the objects of my invention is to provide means. for performingtwo individual operations at will on a single frequency carrier currentcontrol system. A

further object is to provide a coupling unit for carrier current controlover alternating 1 current power distributionlines which will utilizeapparatus already in service and which will eliminate special couplingunits, for connecting the carrier current apparatus to the power line. Afurther object is to provide means whereby the operation of the carriere uiplment will not be affected by any load Iv 1c may be connected tothe power supply me. I 1 The novel features which I believe to becharacteristic of my invention are set forth with particularity in theappended claims. My invention itself, however, both asto itsorganization and method of operation will best be understood byreference to the tol- '25 lowing description taken in connection withthe accompanying drawings, in which Fig. 1 shows diagrammatically acircuit used in connection with the utilization of my invention. Fig. 2shows characteristic curves il- 36 lustrating the voltages acrossdifferent portions of the receivin apparatus. Fig. 3

shows curves representing the voltages at any instant across the glowtubes shown in Fig.

1, while Fig. 4 shows modified form of re- 85 celver.

I have shown in Fig. 1 a power line 1, 2, 3 supplied by a source ofpower 4. The transmitter 5 of Fig. 1 comprises a standard oscillator 6of the required power and frequency and must be of the halfwaveself-rectifying type operating from the service alternating currentsupply. It is coupled to the line over which control is desired in anysuitable manner. A condenser coupling is here shown, but the type ofcoupling is non-essential. The supply to the oscillator is brought inthrough a double-pole -doublethrow switch 7, such that the polarity ofthe alternating current at any instant is reversed by throwing theswitch to the other position.

The position of this switch will then determine which operation is to beperformed at the receiver end. It is essential, however, that the 110volt alternating current supply to the oscillator be either in phase or180 out of phase with the voltage on the two wires on the high voltageline over which control is desired. The most convenient method to obtainthis result is to supply the oscillator of such a transformer issufficiently low to permit a large enough current to flow through theprimary with a reasonably high impressed voltage to cause a fairly largecurrent to flow in the secondary when properly tuned. Yet, the impedanceis'high enough so that it does not affect line conditions enough tointerfere with the operation'of tlie other units from the same line.

Connected across the secondary of the transformer 10 is a series tunedcircuit, com prising a tuning inductance 11 and a tuning condenser 12,whichis tuned to receive the frequency sent out by the transmitter andto step up the voltage on the secondary side to operate the glow tubes13 and 16. It has been found that better than a 1 to 1 ratio can beobtained between the carrier voltage across the line and the carriervoltage across the secondary condenser 12.

The circuits of the two glow tubes 13 and, 16 are connected in parallelacross the condenser 12. One of these circuits consists'of glow tube 13,sensitive polarized relay 14 and relay by-pass condenser 15 which isused to pass theihigh frequency current around the relay winding. Theother circuit is similar and comprisesglow tube 16', sensitive polarizedrelay 17 and relay by-pass condenser 18. 1

The glow tubes or discharge devices 13, 16 comprise, generally, twodissimilar electrodes which are enclosed in a receptacle filled with asuitable'gas, such as neon, at a definite pressure. The particular gasand the pressure are so chosen that if a certain, definite potential isimpressed upon the electrodes a discharge will take place and currentwill flow between ,the two electrodes as long as the potential ismaintained. Because of the dissimilar structure of the two electrodes,however, current will flow in one direction only. In the operation ofthese devices a constant potential is impressed upon them from thealternating current distribution system. The potential thus impressed ischosen at a value somewhat below the value at which a discharge willtake place between the electrodes of the tube. When high frequencycurrent is received and impressed upon the tube, the additionalpotential supplied by the received current is suflicient to produce adischarge through the device and cause a current to flow as long as thehigh frequency current is received.

It has been found that due to inherent characteristics of distributiontransformers the amount of received signals is better with a highervoltage secondary than with a low voltage. The 220 volt secondarywinding is therefore used to supply high frequency to the receiver unit.Since 220 volts will cause the glow tube to glow continuously, thesecondary winding of a polarizing transformer 19 is inserted in serieswith the glow tube circuits as shown in Fig. 1. This transformer is soconnected that its voltage opposes the 220 volts of the distributiontransformer impressed upon the tubes through the tuned circuit. Anyvoltage less than 220 volts may then be obtained across the tubes. Thetwo glow tubes are so connected that they present opposite polarity toany incoming signal, that is the cathode of tube 16 and the anode oftube 13 are tied together and connected to one side of the tuningcondenser 12, while the anode of tube 16 and the cathode of tube 13 areconnected through their respective relays and the polarizing transformerto the other side of tuning condenser 12.

In operating the system described, the output of the halfwaveself-rectifying set 5 is modulated by half of the 60 cycle wave, that isthe oscillator will only transmit high frequency energy during thatportion of the positive half cycleof the alternating current supply thatthe voltage is high enough to causeoscillations. During the remainder ofthe positive half cycle and during the negative half of the cycle noenergy is sent out by the oscillator. The'transmitter output thenconsists of a series of impulses, one occurring during one half of eachcycle.

At the receiver end each glow tube is polarized with a positive voltageon its anode during half the cycle and with a negative voltage duringthe other half of the cycle. When the negative half of the wave isimpressed on the anode, it will, of course, take slightly more thantwice the polarizing voltage to cause the tube to glow, provided it waspolarized to 80% or 90%. During the half cycle that the positive voltageis impressed on the anode, however, only a slight amount of incomingcarrier voltage added to the polarizing voltage is required to cause thetube to glow. Therefore if the impulse of high frequency sent out by thetransmitter 5 occurs during the half cycle that negative voltage isimpressed on the anode of the glow tube, no glow will occur and nocurrent will pass through the relay, unless the high frequency voltageis excessively large. On the other hand, if the impulses of highfrequency sent by the transmitter occur during the half cycle thatpositive voltage is impressed on the anode of the glow tube, the tubewill glow and pass current through the relay with only a very smallvalue of received high frequency voltage. When either relay isenergized, switch 20 or 21 is closed to complete a circuit to operate asignal, an auxiliary relay, or any type of equipment to be controlled.

Assuming that the tube should be polar? ized to 110 volts, the voltageacross the secondary of transformer 19 should be 110 volts, since thatacross the condenser 12 is 220 volts. The resulting voltages across thetwo tubes would then be as shown in Fig. 2. The 220 volts A. C.impressed across the condenser 12 is represented by M, while Lrepresents the 110 volts of the polarizing transformer '19 which is 180out of phase with M. The resulting voltage N is 110 volts across boththe tubes. However, since the tubes are oppositely connected, thevoltages across the two tubes with respect to their anodes at anyinstant are represented by the curves N and N in Fig. 3.

If the switch 7 of the transmitter is thrown to the left of the positionshown the impulse sent out by the transmitter will. say, occur duringthe half cycle that tube 16 has positive potential on its anode and tube13 has negative potential on its anode. Tube 16 will then glow and tube13 will not, unless the high frequency voltage is excessive. However, solittle high frequency is required in the one case and so much in theother, that there is wide range of high frequency voltage valuesthroughout which perfect selection takes place. In actual experienceperfect selection has been obtained with this circuit with a value ofimpressed carrier considerably above the minimum value required tooperate the tube which has positive voltage impressed on it at the timethe carrier impulse is received. Similarly if the switch 7 is thrown tothe right of the position shown,

tube 13 would glow and tube 16 would not.

With the arrangement thus far described the operation may be affected byother loads placed in shunt with the equipment across the secondarywinding of transformer 10. This is due to the fact that the successfuloperation of the system depends upon a large current flowing through thetuned circuit. I have discovered, however, that if small choke coils 22,23 are inserted in series with any additional load, this load will haveno effect on the high frequency currents. These chokes may be verysmall, having a Value of less than 1 Inillihenry, so that they are cheapand easy to build. A condenser 24 of about one microfarad capacity isconnected across the 220 volt lines on the load side of the choke coils,so that if the load is removed, the chokecoils are still connected by arelativcly low impedance at high frequencies and will not detune thereceiver which is tuned to the high frequency. This condenser has arelatively highimpedance at 60 cycles and will not pass much current atthe power frequency.-

In the modification of my invention shown in Fig. 4, a two-circuit tuner25, 26 is employed and any type of coupling 27 to the high voltage linemay be used. The tubes are polarized to opposite polarities at anyinstant by connecting them as shown in Fig. 1. The transmitter is thesame as that in Fig. 1 and like reference characters have been used todesignate like parts in the two figures.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. In a control apparatus, a power supply line, a distributiontransformer connected thereto having a substantial step-down ratio, areceiver including a series tuned circuit connected across the secondarywinding of said transformer thereby to constitute a virtual shortcircuit to high frequency currents, a discharge device connected torespond to potential on a portion of said tuned circuit, a relayconnected to respond to operation of said discharge device and means forsupplying both a polarizing voltage and a high frequency voltage throughsaid transformer to said discharge device.

2. In a control apparatus, a power supply line, a distributiontransformer having a substantial step-down ratio connected thereto, acircuit including a discharge device and a relay connected to thesecondary low voltage winding of said transformer, said discharge devicehaving asymmetric conduc tivity when broken down, means for supplying analternating potential through said transformer to said discharge device,the value of said potential being lower than that required to break downthe discharge device and produce a flow of current in the circuit, andadditional means for supplying through said transformer to the dischargecircuit currents received from a dlstant polnt and there by impressingupon the discharge device apotential great enough to cause current toflow therethrough.

3. In a control apparatus, a power supply line, a distributiontransformer having a substantial step-down ratioconnected thereto, acircuitcomprising a discharge device and a relay connected to thesecondary low voltage winding of said transformer, said discharge devicecomprising a pair of'sepato the secondary winding of said transformerand to said discharge devlce and means for supplying current having afrequency corresponding to said tuned circuit through said transformerthereby to impress a potential upon said discharge device greatenough tocause current to flow therethrough.

4. In a control apparatus, a power supply line, a distributiontransformer havingv a substantial step-down ratio connected thereto, acircuit including a discharge device and a relay connected to thesecondary low voltage winding of said transformer, said discharge dcvicecomprising a pair of separated electrodes surrounded by an attenuatedgaseous medium, and having asymmetric conductivity when broken down,means for supplying an alternating potential through the transformer tothe discharge circuit, the value of the potential being lower than thatrequired to break down the discharge device and produce a flow ofcurrent in the circuit and additional means including a series tunedcircuit connected to the secondary winding of said transformer and tosaid discharge device for supplying to the discharge device currentreceived from a distant point and thereby impressing upon the dischargedevice a potential great enough to cause current to flow therethrough.

5. In a control apparatus, a power supply line, a distributiontransformer having a substantial step-down ratio connected thereto, acircuit comprising a discharge device connected to the secondary lowvoltage winding of said transformer, means for supplying a polarizingelectromotive force through said transformer. and said circuit to saiddischarge device, means to impress an opposing electromotive force uponsaid discharge device, the; resulting electromotive force being lessthan that required to break down the discharge device, and means forsupplying an additional electromotive force through said transformer andsaid circuit to the discharge device thereby to effect its operation anda relay connected to respond to operation of the discharge device;

6. In a control apparatus, a power supply line, a receiver connectedthereto, comprising a plurality of oppositely connected asymmetricallyconducting discharge devices, means for supplying alternating potentialto said power line to polarize said discharge devices means for imaressin an additional electromotive force upon said discharge devicesduring either of the like half cycles of the alternating potentialthereby selectively to effect the operation of the discharge devices,and a relay connected to operate responsively to each discharge device.

7. In a control apparatus, a power supply line, a distributiontransformer connected thereto, a receiver including a circuit tuned fora certain frequency and connected to the secondary winding of saidtransformer, a load connected to said secondary winding and means toprevent the application of current of said certain frequency to saidload, and additional means to prevent variations in impedance of saidload from effecting said tuned circuit.

8. In a control apparatus, a power supply line, a distributiontransformer connected thereto, a receiver including a circuit tuned fora certain frequency and connected to the secondary winding of saidtransformer, a load connected to said secondary winding, means incircuit with said secondary winding to prevent the application ofcurrent of said certain frequency to said load, and a condenserconnected to said secondary winding and arranged between said means andsaid load.

9. The combination of an alternating current distribution system, andtransmitting means for impressing currents of a different frequency uponsaid system during alternate half cycles of the alternating current waveand for interrupting said currents during opposite half cycles, areceiver comprising a plurality of asymmetrically conducting dischargedevices connected to said system and having alternating potentialimpressed thereon from the system, said devices being reverselyconnected with respect to said potential, and means for controlling theoperation of the transmitter to cause it to operate during either halfcycle thereby selectively to control the operation of said dischargedevices.

10. The combination of an alternating current distribution system. and ahalf wave selfrectifying transmitter connected thereto for impressingcurrent of a different frequency upon said system, a receiver comprisinga plurality of asymmetrically conducting dis charge devices connected tosaid system and having potential of the frequency of said systernimpressed thereon, said devices being reversely connected withres ct. tosaid potential and reversing means fli r controlling the operation ofthe transmitter and for selectively controlling the operation of thedischarge devices.

11. The combination of an alternating current supply line and a singlehalf wave selfrectifying transmitting means for superimposing a seriesof impulses upon the potential of said line during a' portion of a halfcycle of the alternating current supply, and means for reversing theenergization of said single transmitting means to vary the time relationof the impulses with respect to the polarity of the potential in thesupply system.

12. The combination of an alternating cur rent supply line, andtransmitting means energized from said line for transmitting a series ofimpulses over said line during a portion of a half cycle of thealternating current supply, a receiver comprising a plurality ofoppositely connected asymmetri cally conducting discharge devicesconductively connected to-said system, and means for controlling thetime relation of the impulses with respect to the polarity in the supplysystem thereby selectively to control the operation of the dischargedevices.

13. The combination of an alternating current distribution system, atransmitter connected to operate during a portion of like half cycles ofthe alternating current wave to impress current of a different frequencyupon said system, a receiver including a pluralityof reversely connectedasymmetrically conducting devices connected to respond to said currentsof different frequency and means for reversing the operation of saidtransmitter with respect to the alternating current wave of thedistribution system and for selectively controlling said devices.

14. In combination, an alternating current distribution system, aplurality of asymmetrically conducting gaseous discharge devices, eachof said devices being conductively connected to the system in oppositerelation, means whereby an alternating voltage is applied to saiddevices which is insufiicient to cause the devices to break down, meansfor,

adding additional voltage to either the positive or negative half cycleof the alter}; ting current wave to cause one of said deaices to breakdown dependent upon the half cycle to which the voltage is applied andmeans associated with each device connected to operate in response tobreak down of the associated device.

15. In combination,-a power distribution system, a plurality ofasymmetrically conducting discharge devices, each of said devices beingconductively connected to the system in opposite relation, means forapplying alternating potential to said devices the value of which isproximate to but less than the value at which said devices break downand become conducting, means for applying an additional electromotiveforce during either the positive or negative half cycle of saidalternating potential thereby to cause one of said devices to break downand become conducting dependent upon the half cycle during which theadditional potential is applied, and means associated with each deviceand connected to operate in response to the break down of the associateddevice.

In witness whereof I have hereunto set my hand this nineteenth day ofJanuary, 1925. AUSTIN V. EASTMAN.

